1. Field of the Invention
The present invention relates to a battery terminal.
2. Description of the Related Art
A conventional battery terminal, as disclosed in Japanese Utility Model Publication No. 6-88050, includes an arcuate fastening portion that can be fitted on a battery post. Extending portions extend radially outward from the opposite ends of the fastening portion. A bolt extends between the extending portions and a nut can be threaded onto the bolt. Thus, a tightening of the nut on the bolt brings the extending portions closer to each other to reduce a diameter of the fastening portion.
A proper fastening torque applied to the nut ensures that the extending portions have a proper spacing, and that the radius of curvature of the fastening portion is set to a proper value. Consequently, the torque normally is controlled to avoid excessive fastening of the battery post. However, an excessively large fastening torque can be applied to the nut of the above described battery terminal. Forces created by this high torque can bring the extending portions of the battery terminal too close to each other, thereby excessively reducing a radius of curvature of the fastening portion. Additionally, the battery post may undergo an abnormal deformation.
Although the torque typically is controlled, it is necessary to account for a situation where the torque exceeds the normal range. For example, a stopper may project from one extending portion sufficiently to contact the other extending portion while the fastening torque still lies in the normal range. Thus, even if the fastening torque exceeds the normal range, the stopper limits the approach of the extending portions toward each other.
However, the fastening torque can be sufficiently large to deform the stopper. As a result, the stopper cannot prevent the adverse effects of all excessive fastening forces.
In view of the above situation, an object of the present invention is to improve reliability of an excessive fastening preventing function.
The subject invention is directed to a connection device for a battery terminal or battery post. The connection device comprises at least one arcuate fastening portion that can be fitted on a battery post and at least two extending portions that project from the arcuate fastening portion. The extending portions preferably project radially outward from opposed ends of the arcuate fastening portion. A fastening means is provided for reducing the diameter of the fastening portion by bringing the extending portions closer to each other. In a preferred embodiment, the fastening means comprises a bolt and a nut.
The extending portions of the connection device comprise primary and secondary stoppers for limiting movement of the extending portions toward each other. The primary stopper may be brought into a contact state when the space between the extending portions is narrowed to a specified degree. The secondary stopper may be brought into a contact state when the space between the extending portions is narrowed further from the state where the primary stopper reaches its contact state. Such a further narrowing may be due to a deformation of the primary stopper and/or the extending portions.
The extending portions are brought closer to each other and to a proper spacing when a proper pre-established torque is applied to the nut and the bolt of the fastening means. Thus, the battery post is fastened with a proper strength.
The extending portion may be brought closer than the proper spacing if the applied fastening torque exceeds the proper value. However, the primary stopper is brought into the contact state to restrict any further approach of the extending portions with respect to each other while the space between the extending portions is still in a permissible range. This prevents the battery terminal from being excessively fastened to the battery post.
The fastening torque conceivably could exceed a value bearable by the primary stopper. In this situation, the extending portions are brought closer to each other due to a deformation of the primary stopper or the extending portions. However, the secondary stopper is brought into its contact state to restrict any further approach of the extending portions toward each other. This contact state of the secondary stopper occurs while the spacing between the extending portions still lies in the permissible range where fastening to the battery post is assumed to be normal. Thus, a fastening force on the batter post will not exceed the permissible range.
The primary and secondary stoppers enable two excessive fastening preventing functions to be provided. Therefore, reliability of the excessive fastening preventing function is higher as compared to a case where only one stopper is provided.
An elastic restoring force preferably acts on the deformed primary stopper and/or the extending portions to separate the extending portions away from each other while the secondary stopper is restricting any further approach of the extending portions toward each other. Thus, the approach-restricting function is better as compared to a case where only the secondary stopper restricts the approach of the extending portions.
The secondary stopper preferably is configured such that the fastening torque that is required to deform the secondary stopper exceeds the fastening torque that is required to fracture the bolt. Thus, the fastening torque will fracture the bolt before the fastening torque deforms the secondary stopper. Accordingly, deformation of the secondary stopper can be prevented.
The primary stopper may comprise a rib formed by bending an outer end of one extending portion at an angle different from 0xc2x0 or 180xc2x0, preferably substantially at right angles. The primary stopper may further comprise a receiving surface formed on the other extending portion and disposed for contact with the rib.
The secondary stopper preferably comprises substantially tubular projections formed on the extending portions to project substantially toward each other. The tubular projections preferably are formed by applying burring to edges of bolt insertion holes of the respective extending portions. Tubular projections formed by burring have excellent strength, and therefore are suitable as the secondary stopper, which is required to be stronger than the primary stopper.
Most preferably, the extending portions each are formed with a primary stopper and a secondary stopper.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments.